Re: Microsoft Z80 Card

[pausch@saaf.se (Paul Schlyter)]

In article <441b5b3b$0$7748$9b4e6d93@newsread4.arcor-online.net>,
Linards Ticmanis  <ticmanis@gmx.de> wrote:

>> 4 - does the apple CP/M work with SCSi drives? ( and the CFFA, if i 
>> manage to get one ) or am i stuck with just floppies?
> 
> No idea, sorry. I'd guess not.

The standard Apple CP/M distribution supports only floppies, that's
correct.  However, when compared to other OS'es of that time, CP/M was
unusually versatile if you wanted to add a new kind of disk drive to
it.  Get a copy of the CP/M Alteration Guide e.g. here:

    http://www.cpm.z80.de/drilib.html

There you'll find descriptions of how to correctly set up the disk
parameter tables in CP/M's BIOS to make your new drive recognizable
by CP/M.  To that, you must add code which actually accesses your new
drive - naturally that is system specific and cannot be covered in
a generic manual.

Formatting a new drive for CP/M is easy: just make sure all the
sectors are there, then fill them all with hex E5 bytes.

CP/M 2.x is able to support disk volumes up to 8 MBytes large.  If
your disk is larger than that, CP/M will be able to access only the
first 8 MBytes of the disk.  Partitioning the disk may help here, but
since CP/M knows nothing about disk partitions, you must implement
that yourself in the code which is called by CP/M's BIOS.  It's
probably most convenient to make each disk partition appear as a
separate CP/M drive.

Finally, to have your modified CP/M start up nicely, you have two
options: either write your modified CP/M to the boot tracks on your
floppies.  Or run some programs which modifies CP/M in RAM after the
normal CP/M boot has finished.

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